A Lao military helicopter went missing in mountainous areas in the vicinity of the Lao province of Xaysomboun Monday afternoon, multiple sources told Xinhua on Tuesday.

The aircraft was declared missing Monday after losing contact with ground during a flight from Vientiane to the eastern province of Huaphan, sources said, adding that some believe that the chopper has crashed.

Some 20 personnel were believed on board.

Officials have yet to confirm or release further details of the incident.